1. Field of the Invention
This invention relates to flashlights and, more particularly, to rechargeable flashlights, i.e., flashlights powered by rechargeable batteries, wherein the rechargeable batteries can be recharged while they are inside of the flashlight. This invention also relates to a recharger for recharging rechargeable flashlights.
2. Description of Related Art
Application Ser. No. 08/738,858, filed on Oct. 28, 1996, and titled "Tactical Flashlight," discloses a flashlight especially adapted for use by law enforcement personnel. This patent application is co-pending with and has the same assignee as the present application. The flashlight disclosed in that application has a number of advantageous features, including a lamp and switch mounted on circuit boards for better electrical contact, an adjustable focus that would not be altered inadvertently, and a switch positioned to enhance ease of use in law enforcement situations. The flashlight is preferably powered by a pair of 3 volt lithium batteries. However, because these batteries are not rechargeable, they must be continuously replaced, thereby creating the burden on law enforcement personnel of having to maintain a supply of replacement batteries and having to determine when the batteries need to be replaced.
It is also known in the art to provide rechargeable flashlights, i.e., flashlights powered by an assembly of rechargeable batteries that can be recharged while they are inside the flashlight. For this purpose, the rechargeable flashlights are typically provided with a pair of recharging contacts that are electrically connected to the positive and negative terminals of the rechargeable battery assembly. Examples include the flashlights disclosed in U.S. Pat. Nos. 4,092,580; 4,282,562; 4,357,648; 4,605,993; 5,008,785; 5,629,105; and 5,772,309. A disadvantage of such rechargeable flashlights, however, is that the most commonly used rechargeable cells, nickel-cadmium cells, have a voltage that is much lower than that of lithium cells. As a result, the lamp does not normally illuminate as efficiently when using the same number of cells.
Sharma et al., U.S. Pat. No. 5,646,484 disclose a portable illumination system for use in applications that require a high output light source, such as heliport markers, runway lights, warning lights, road hazard and obstruction lights. The portable illumination system disclosed therein includes a DC/DC converter to step up the battery voltage to a level required to drive a high output light source, such as a 120V incandescent bulb. Sharma et al., however, do not disclose the DC/DC converter incorporated into a compact flashlight, nor do Sharma et al., disclose means for recharging the batteries while they are inside of the portable illumination system.
Accordingly, a need exists to provide a flashlight that is powered by rechargeable batteries that can be recharged while inside of the flashlight that can also provide the illumination efficiency provided by similarly-sized non-rechargeable batteries, such as lithium cells.